Soren R. Schipper1,2, Blake Ramsby1, Florita Flores1, So Young Jeong2, Muhammad Abdul Wahab1, Andrea Severati1, Andrew Negri1, Guillermo Diaz-Pulido2
1Australian Institute of Marine Science, Townsville, Queensland 4810, Australia
2 Griffith School of Environment, Coastal and Marine Research Centre, and Australian Rivers Institute – Coast and Estuaries, Nathan Campus, Griffith University, Brisbane, Queensland 4111, Australia
Crustose coralline algae (CCA) are fundamental to the health of tropical marine ecosystems in that they are the mortar binding reef together as well as species-specific mediators of larval settlement and metamorphosis for corals and other invertebrate taxa. It is well established that light is an important driver in marine ecosystem processes, yet little is known about how light quality and intensity impact CCA communities, particularly in aquaculture settings. In this study, we tested the influence of light spectra and irradiance on CCA community structure and composition growing on artificial substrates in culture. Settlement tiles were conditioned with CCA in flow-through tanks at the Australian Institute of Marine Science (Townsville), and then separated into aquaria exposed to three different light spectra (blue dominated, green dominated, and full-spectrum) at four distinct irradiance levels (ranging from 5 to 220 umol). Algae were identified using morpho-anatomy and DNA sequencing. Initial results indicated that light quantity impacted community composition and morphology of CCAs, but spectrum had no considerable influence on species composition. Communities were dominated by Lithophyllum sp. followed by Porolithon spp. and Mesophyllum spp. These results may help inform optimal light conditions for propagating target CCAs for the purpose of settling coral in aquaculture and reseeding coral populations in degraded coral reefs in the Great Barrier Reef.